Consequences of port mismatch and finite isolation on power combining

In solid-state power amplification, power combining is an important issue since the output powers from individual transistors are too small for many transmission applications. An important aspect of power combining is the combining efficiency being the ratio of the power delivered to the load to that available from the sources connected to the input. In a practical power combiner, waves incident on the input ports are scattered to all ports including the output port. The paper discusses the effects of port mismatch and finite combiner isolation on combining efficiency. For a lossless power combiner, it is shown that the efficiency may be optimised by optimising the matching at the combiner output